I just finished my suspension refresh last week. My car is an 88 930 and as far as I can tell all suspension parts were original. I did the following:
Replaced all front and rear swaybar bushings. (easy and cheap)
Replaced front control bar bushings (cheap, but a little more difficult)
Replaced ball joints and tie rod ends. (easy and not too expensive)
Replaced rear control arm bushings (cheap, but royal PITA for me)
Replaced spring plate bushings (did this last year and it was a PITA)
Replaced rear sway bar drop links.
Replaced front strut caps.
Sent shocks/struts to Bilstein to rebuild. Cost just over $100 per and they look brand new. Took like 6 weeks though. See pic below.
This is pretty much all the rubber suspension parts in your car.
Yes, you can go upgrade with monoballs, polybronze bushings and higher end components, but if you are nearly all street, all you will get is a harsh ride with no benefit for the street, IMO. Every single part was sourced from our host and the only non Porsche parts were the control arm and the rear trailing arm bushings (elephant racing).
I still have my motor out, so I haven't tested it yet, but I expect a tighter, more precise suspension that handles like it did out of the factory without breaking the bank.
Except for waiting on the shocks and getting the parts in, everything else was done in about 2 weeks of me working at night and tackling one task at a time.
You can also refinish the control arms, spring plates, etc. if you have the time and patience. I don't.
My only suggestion would be that if you decide to upgrade to monoballs and the like, work with a specialist that knows how to put a suspension kit together for your car the way you drive it. All the parts must work together and if you just upgrade some components, you may well be disappointed with the result.
